Well as you can see it came from that hatred pouch on that girl that died on the previous episode. On his last words she said ” she regret that she did not take his revenge on wang lin ” so therefore he left that pouch and after she died she left a last message of how she did raise and cultivate that hatred.

After MC opened that pouch he did not destroy it instead he reverse the hatred i forgot what it is call, and then MC gave him a new life to experience. not to be a cultivator.

Hope this helps

But who or what is the “one” or “no one” they speak of?